This invention relates to a dust collector-equipped power cutter and in particular to a portable type power cutter having a cutter disk that is driven by a prime mover, such as a small air-cooled two stroke internal combustion engine or an electric motor, a dust-sucking fan, and a dust hose for discharging the dust sucked by the fan.
A conventional portable type power working machine of this kind, which is provided with a dust collector, is generally comprised of a main body provided with a prime mover, a cutter disk rotated by the prime mover, a safety cover encasing part of the cutting edge portion and parts of both sides of the cutter disk so as to form a dust passage between the safety cover and the cutter disk, a dust-sucking fan attached to the safety cover for sucking dust generated when the cutter disk is cutting a workpiece and discharging the dust through a dust-discharge passageway, and a dust hose for transferring and discharging dust sucked by the dust- sucking fan. One example of such a power cutter is disclosed in Japanese Patent Publication H/7-14570.
In the use of such a conventional power cutter, the dust generated in the course of cutting, for example, a concrete product, is sucked through the dust discharge passage formed between the cutter disk and the safety cover by the sucking action of the dust-sucking fan, which is rotated by the prime mover, and then discharged from the dust-sucking fan through the dust hose in a rearward direction from the power cutter. In some cases, an air permeable dust bag, such as a cloth bag, is attached to the distal end of the dust hose so as to separate dust particles from the dusty air transferred under pressure through the dust hose, thus leaving the dust particles in the bag while discharging clear air free of dust from the bag.
However, the dust hose attached to the aforementioned dust collector-equipped power cutter is formed of a single continuous piece of hose, the proximal end of which is fastened to the dust-discharging portion of the dust-sucking fan, while the distal end extends rearwardly from the power cutter. Therefore, it is very troublesome to deal with this long dust hose, and at the same time, very inconvenient for the storage thereof in a warehouse or other place or for the transportation thereof.
Furthermore, in a cutting operation in an environment where the aforementioned dust bag is not required to be employed, it may be desirable to use a dust hose of a short length rather than the aforementioned long dust hose. In such a case, a short dust hose is separately prepared in advance and substituted for the long dust hose. However, this exchanging operation is very troublesome in the conventional power cutter.
Furthermore, the dusty air containing dust particles which has been introduced into the dust bag is then separated, leaving the dust particles in the dust bag, and allowing only dust-free air to be discharged from the dust bag. However, when the cutting operation is interrupted or terminated, the power transmission to the dust-sucking fan is cut off, which stops the rotation of the dust-sucking fan, thus resulting in the stoppage of air flow toward the dust bag. At this moment when the air flow toward the dust bag is interrupted, the interior of the dust bag is still kept in a high pressure condition due to the air flow that has been introduced in the dust bag before the cut-off of the dust-sucking fan. Therefore, due to this high pressure inside the dust bag, the dusty air containing dust particles and existing in the dust bag flows backward, i.e., toward the dust-sucking fan, and is discharged outside through the safety cover, thus annoying the operator.
The same problem of back-flow of dusty air occurs when the operator steps on the dust bag accidentally.